The invention is directed to an apparatus for the continuous measurement of ion concentrations by means of ion sensitive electrodes in solution, particularly for the measurement of cyanide ion concentration in strong hydrochloride solution in the presence of cyanogen chloride. The apparatus consists essentially of an electrode containing measuring cell, a dosaging device for the proper control of the solution to be measured and a connecting pipe for withdrawal of the solution being measured from the processing vessel.
It is known to determine ion concentrations in liquid media with the help of sensitive electrodes, which is particularly important for the control of continuous processes. Of particularly significance is a measuring method and a corresponding apparatus for the continuous measurement in corrosive media. Above all, is important the continuous determination of cyanide ion concentration in chemical syntheses, as well as e.g., continuous analysis of waste water.
These types of apparatus are known in the practice (e.g. K. Cammann; das Arbeiten mit ionenselektiven Elektroden Springer-Verlag, 1967, pages 190-194; F. Oehme, CZ-Chemie-Technik, 1974, pages 27-34). Such apparatus generally consist of a measuring cell which contains essentially the sensitive electrodes, and a dosaging device in which the solution to be measured is treated with conditioning solutions for the proper control of the solution to be measured. The conditioning solutions normally contain reagents for establishing a specific pH, sequestering agents for masking disturbing ions and other auxiliary reagents. These solutions are sucked in via electrical pumps, preferably tubular pumps, mixed, in a given case by means of a stirrer, and fed to the measuring cell.
The known apparatus, however, have the disadvantage that they are very prone to problems with strongly corrosive and gas forming liquids, particularly by using moving parts, such as pumps, stirrers or magnetic valves.
However with corrosive media the question of material plays a decisive role. Metals and flexible synthetic resin materials, as they are used, e.g. for hose connections, frequently lead to failures of the apparatus in question. These can have serious consequences for the entire process since the subsequently connected control devices with the failures of the measuring apparatus receive false information.
Furthermore the down time of these apparatuses with mechanically moving parts is relatively long and leads to a very sluggish control behavior.
Therefore it was the problem of the present invention to provide an apparatus for the continuous measurements of ion concentrations by means of ion sensitive electrodes in solutions, particularly for the measurement of cyanide ion concentrations in strong hydrochloride solutions in the presence of cyanogen chloride, which consists essentially of an electrode containing measuring cell, a dosaging device for the proper control of the solution to be measured and a connecting pipe for withdrawal of the solution to be measured from the processing vessel, which has to the least extent possible moving parts and whose down time is as short as possible.